I think it's a fashion thing with a thin veneer of eye strain reduction (since, AFAIK, there's little conclusive evidence dark mode matters here)
Access your data for all websites
Access browser tabsAlso, try Stylus with the "Hacker News Readable Dark" style.
Maybe it's because I'm getting older, but staring at a blinding white computer monitor inches from my face all day as a software engineer HURTS. Like, literally hurts after a while.
Dark mode is much easier on the eyes.